Liliums--The True Lilies

Did you know that many plants that have “lily” as part of their common name (daylilies) are not “true” lilies?  True lilies belong to the genus Lilium.  Cultivated for more than 5,000 years, liliums are one of the most treasured species among all perennial flowers.  Cultivated lilies are classified into eight divisions based upon the number of blooms per stem, shape and presentation, of the individual flowers, and a separate class exists for species lilies.

Asiatic and Oriental lilies are the two most popular types of lilies for northern gardens. As the names suggest, Asiatic lilies have their origins in several areas in Asia, while the Oriental lilies started from a few species native to Japan.  So how can you easily distinquish what type of lilium you have?  Many Oriental lilies have raised papillae (whiskers)  in the petal nectaries (small pockets at interior base) of flower. The liliums shown here are Asiatic.

Asiatic lilies are among the easiest to grow. They're very hardy, need no staking, and are not particu- larly fussy about soil, as long as it drains well.  If you like flowers which multiply prolifically, bloom early, and has bright powerful colors, then Asiatics may be for you.  On the other hand, if you like heavenly scented flowers, Oriental lilies may be for you.  Oriental lilies tend to be more aromatic,  but are a bit trickier to grow and tend to spread much more slowly.

Understanding the difference between Asiatic and Oriental liliums will help you make the right choice.  Asiatics tend to bloom earlier with flowers of 4 to 6 inches in size.    Orientals bloom tend to bloom later in the season with fragrant flowers of  5 to 10 inches in full bloom. Regarding the height of the plants, the Asiatic lilies may be 2 to 4 feet tall, while the Oriental lilies tend to be taller.  Asiatics have the greatest range of colors and more variance in flower shape and bloomtime, but they usually have little or no frangrance.  Planting both can extend your lilium season.

Where, When and How to Plant Your Lilium

Lily bulbs may be planted in spring or in the fall, usually from mid-September through mid-October. If you find hardy lilies growing in containers, you may add them to your garden throughout the growing season. When buying locally, select firm, plump bulbs with roots attached. Plant them as soon as possible. Bulbs never go completely dormant so they must not dry out before planting.
Both Asiatic and Oriental lilies need five to six hours of sunlight every day. Oriental varieties, however, prefer afternoon shade too.

For best effect, plant lilies in groups of three or five identical bulbs. Space them eight to twelve inches apart, keeping groups three to five feet apart, depending on the vigor and size of the lilies. Plant small lily bulbs two to four inches deep and large bulbs four to six inches deep, measuring from the top of the bulb. Divide and replant large clusters of bulbs when the number of flowers start to diminish.

Never plant lilies where standing water collects after heavy rainfall. Well-drained soil is an absolute must. Add lots of organic matter to clay soil to create a raised area with improved drainage. Incorporate organic matter into light, sandy soil also, to help hold onto nutrients and prevent it from drying too rapidly.

Before winter, mulch over newly planted bulbs with four to six inches of loose, weed-free compost, leaves, or wood chips. This delays soil freezing and allows roots to continue growing longer. Mulch also insulates the soil against fluctuating temperatures, delaying the emergence of frost-tender shoots in spring.

Tiger Lilies (Lilium lancifolium) should be kept apart from other lilies since they can be carriers of viruses.

Caring for Your Lilies

In spring, leave mulch in place until the danger of hard frost has passed. If lily shoots grow through the mulch, start to remove it gradually – but leave it nearby so you can cover them again if another hard frost is predicted.

Fertilize the soil each spring with a phosphorus-rich formula such as 5–10–10. Slow-release fertilizers work well. Always follow label instructions when applying fertilizer.

Lilies usually have few pests, but rabbits and slugs can be a menace to emerging shoots. Aphids – small sucking insects – can also cause problems for flower buds. Carefully wash the affected plants with water sprayed forcefully from your garden hose to remove aphids.

Botrytis blight, a fungal disease, causes reddish-brown leaf spots and is often the result of damp weather or evening watering. When you water at night, the leaves often stay wet until the sun comes out and dries them the following morning, encouraging foliar diseases) Whenever possible, water early in the day, or water at the base of the plant rather than over head. Adequate spacing between clusters of lilies also promotes good air circulation and may help prevent disease.

Deadhead flowers as they fade, by breaking them off carefully. That way, none of the plant's energy is “wasted” on seed production. Do not remove stems or foliage, though. They'll continue to put energy into the bulb as long as they remain green. Remove old foliage in late fall or early spring by cutting down the dead stalks.  Lilies need well-drained soil in an area that receives sun or part shade. Lilies, like clematises, prefer their flowers and leaves in the sun while their roots prefer shade. They need to be kept moist. Lilies can be planted either in the fall or spring, whenever the bulbs are available.

Handle the bulbs carefully because the scales can be easily broken off. Space them 6 to 10 inches apart. Plant lilies with 4 to 6 inches of soil covering the bulb. This allows them to form roots along their stems. Tall lilies should be staked and protected from high winds. Mulch well to keep lily roots cool. Remove blooms when they die to prevent seedpod formation. Cut stems off at ground level after they turn brown, but never cut them down while the leaves are still green.

Dividing Bulbs

Lily bulbs do not need to be divided every year. Generally, every two to three years is sufficient. If you notice that your garden is overcrowded and the lilies are blooming less than they were in previous years, then it's time to divide your bulbs. They are all using a limited amount of nutrients and water in a limited amount of space and need more room to thrive.

Asiatic Lennox Lilium

When it's time to divide your bulbs, they are best divided in the fall, just after the foliage has turned yellowish-brown. This way, the plant has had a sufficient amount of time to absorb lots of sunlight and convert it to sugar (plant food) through the process of photosynthesis before you cut off the foliage and dig up the bulbs for division. You can also divide your bulbs during other times of the year--early spring is the second best time of year--however, your bulbs may experience stress, especially if you divide the bulbs in the middle of their growing season. Divide lily bulbs with your hands by pulling off attached bulbs. Do not use a knife. Throw out any bulbs that are rotted or damaged.

After you have dug up your bulbs and divided them, it is essential that you replant them within a few days.  Plant lily bulbs about 4 to 8 inches deep with the tips facing up. Space multiple plants 10 to 12 inches apart.

Sources:
http://www.extension.umn.edu/distribution/horticulture/dg1112.html
http://www.ehow.com/way_5607063_divide-lily-bulbs_.html